The invention relates to an electronic part comprising at least two coils. The invention relates to an electronic device comprising such electronic parts. The inventor further relates to a mobile phone.
In recent years, mobile telephones have been available commonly, which transmit and receive two different frequency bands. These mobile telephones may be provided with, for example, a pair of low-pass filter (referred to as LPF hereinafter) and high-pass filter (referred to as HPF hereinafter) that will separate the received signals into lower frequency signals and higher frequency signals. In this case, if both filters are differently implemented onto different parts, it may become rather difficult to realize a compact size and a low weight for mobile telephones. Accordingly, recent techniques tend to integrate LPF and HPF into a single chip part. However, if such integration is not carefully designed, respective frequency characteristics of the LPF and the HPF tend to fluctuate due to the interference between the LPF and the HPF. For this reason, a shield electrode between the LPF and the HPF may be useful in order to eliminate such interference between the LPF and the HPF. Thus, a shield electrode can be used to allow for the integration of the LPF and the HPF.
Nevertheless, there are severe limitations that are posed upon a size in height for electronic parts embedded into such devices as mobile telephones requiring a small size. For example, there exists a problem that it may be difficult to adapt the height of integrated chip parts within a desired dimension of height if integrated chip parts are produced through integrating LPF and HPF in a vertical direction. Accordingly, it seems to be better to arrange the LPF and the HPF together in parallel in the horizontal direction to produce an integrated chip part. However, because such chip parts are usually produced by stacking dielectric layers on which electrode patterns are printed, there still exist a problem that it may be quite difficult to form a shield electrode between the LPF and the HPF when those LPF and HPF should be together laid down laterally (namely horizontally).
To resolve the above-mentioned problem, the Japan Patent Application No. 1998-117117 discloses a high frequency part wherein respective patterns of the inductance and the capacitance are so arranged as to eliminate the interference between the LPF and the HPF without providing any shield electrode. However, the disclosed part should be designed to broaden the space between the LPF and the HPF in order to eliminate the interference between the LPF and the HPF, which may be resulted in a difficulty in achieving the compact size of such part.
Accordingly, it is an object of the invention to provide an electronic part that needs no shield electrode but can have a smaller size and also to provide an electronic device comprising a plurality of such electronic parts.
To achieve the above-described object, the invention provides an electronic part that comprises a substrate that contains at least one material selected from a dielectric material and a magnetic material, two or more coils, formed in the inside of the said substrate, that take the form of a spiral and extend in a predetermined direction, and two grounding electrodes that are located in the inside or the outer surface of the said substrate, the said two grounding electrodes being aligned in the said predetermined direction in such a way that the two or more coils are located between the two ground electrodes.
The two or more coils of the inventive electronic part are of a type of coil that takes a spiral form and extends to a predetermined direction, in addition, two grounding electrodes are aligned in that predetermined direction with the two or more coils located between the two ground electrodes. Since any extension of the magnetic flux generated by each of the coils may be limited by those two grounding electrodes, a degree of coupling of such magnetic flux may be increased. Therefore, when the inventive electronic part is given some characteristics like a filtering characteristics, a degree of coupling of the magnetic flux generated by these coils might be considered as a major decision factor to determine the filtering characteristics. Thus, it will be possible to give a desired filtering characteristics to the inventive electronic part by considering a degree of coupling of the magnetic flux generated by these coils to design such filtering characteristics. Therefore, in order to gain a desired filtering characteristics, the inventive electronic part is designed in such a way that coupling of magnetic flux generated by these coils is positively promoted. By doing so, it will be possible to locate two or more coils so closely each other as to increase a degree of coupling of the magnetic flux generated by coils, which may be resulted in a compact size of the electronic part.
Therefore, in the inventive electronic part, the said two or more coils are preferably formed within such area of the said substrate that is sandwiched by the said two grounding electrodes. With such structure, the two grounding electrodes may efficiently function as a shield electrode and as a result magnetic flux generated by coils could be coupled without any significant influence from the external environment.
Besides, the said two or more coils of the inventive electronic part is preferably designed to make a spiral form having at least one round. Thus, the magnetic flux generated by each coil may be further reinforced.
The inventive electronic part may further comprise an external electrode that is located in the said outer surface of the said substrate, wherein at least one coil among the said two or more coils maintains no contact with the said external electrode. No contact of a coil with the external coil is allowed in the inventive electronic part.
Besides, the electronic part may preferably comprise an internal electrode that is located between one of the said two grounding electrodes and at least one coil among the said two or more coils, so that such capacitor that comprises the internal electrode and the grounding electrodes can be formed.
Furthermore, the inventive electronic part may preferably comprise a first filtering means, located in the said inside of the said substrate, that contains at least one coil among the said two or more coils and a second filtering means, located in the said inside of the said substrate, that contains at least one other coil than the said coil or coils contained in the said first filtering means, wherein the said first filtering means and the said second filtering means have the respective pass-bands belonging to the different frequency ranges. With such structure, it will be possible to separately retrieve, from one electronic part, some signals each of which has a unique frequency band belonging to a different frequency range.
In addition, the invention provides an electronic device comprising a first electronic part and one or more second electronic parts mounted on the said first electronic part. Furthermore, in the complex electronic device, at least one of the said first and second electronic parts comprises a substrate that contains at least one material selected from a dielectric material and a magnetic material, two or more coils, formed in the inside of the said substrate, that take a spiral form and extend in a predetermined direction and two grounding electrodes, located in the inside or the outer surface of the said substrate, that are aligned in the said predetermined direction in such a way that the two or more coils are located between the two ground electrodes.
In particular, the inventive electronic device is designed to mount one or more second electronic parts on the first electronic part, so that when such electronic device is mounted on a circuit board, it may also be possible to mount second electronic parts on that circuit board only by providing a sufficient area to mount the first electronic part on the circuit board. As a result it may be possible to efficiently mount a number of electronic parts on the substrate.